WASHINGTON (REUTERS) - Facebook on Saturday (July 17) defended itself against US President Joe Biden's assertion that the social media platform is "killing people" by allowing misinformation about coronavirus vaccines to proliferate, saying the facts tell a different story.

"The data shows that 85 per cent of Facebook users in the US have been or want to be vaccinated against Covid-19," Facebook said, in a corporate blog post by Guy Rosen, a company vice-president.

"President Biden's goal was for 70 per cent of Americans to be vaccinated by July 4. Facebook is not the reason this goal was missed."

Covid-19 misinformation has spread during the pandemic on social media sites including Facebook, Twitter and Alphabet-owned YouTube.

Researchers and lawmakers have long accused Facebook of failing to police harmful content on its platforms.

"They're killing people... Look, the only pandemic we have is among the unvaccinated. And they're killing people," Biden told reporters at the White House on Friday when asked about misinformation and what his message was to social media platforms such as Facebook.

The company has introduced rules against making specific false claims about Covid-19 and vaccines for it, and says it provides people with reliable information on these topics.

The Delta variant of the coronavirus is now the dominant strain worldwide, accompanied by a surge of deaths around the United States almost entirely among unvaccinated people, US officials said on Friday.

American cases of Covid-19 are up 70 per cent over the previous week and deaths are up 26 per cent, with outbreaks occurring in parts of the country with low vaccination rates.